I have tried to grasp the concept of calculating the RMS/Impedance for my sub. But I am not sure how much power my sub is being fed (obviously a professional installed it)

My Sub +++
JL Audio 10w3d (1)
It is a dual voice coil
It is suppose to recieve around 250 RMS
It is currently wired at 3 ohms

My Amp +++
RF p3002
» 2-channel car amplifier
» 75 watts RMS x 2 at 4 ohms (150 watts RMS x 2 at 2 ohms)
» 300 watts RMS x 1 bridged output at 4 ohms (4-ohm stable in bridged mode)
» variable high- and low-pass crossovers (40-400 Hz at 12 dB/octave)
» variable Punch Bass (0-18 dB boost at 45 Hz) with wired remote
» Tri-way capable (Tri-Way Crossover required)
» MOSFET power supply and output devices
» fuse rating: 40A x 1

Thanks

First off take a DMM and set it to ohms and find out how many ohms one coil has... unless it is written on the magnet... you are saying that its wired at 3 ohms, which could be the case if it is a 6ohm DVC wired in paralell... then my next assumption is that the 3ohm load is then wired in bridged mode on your amp... except that in bridged your amp is only stable to 4ohms... if that is the case the speaker will be drawing in excess of 300rms, the question is for how long...? anyway enough of my banter find out the impedance of the coils and someone can sort you out

I dont have a DMM on me but..

We did measure it a while ago and I think that the voice coil is 0.9 ohms

I am also certain he has wired it in parallel

keep in mind that the sub is wired at 3 ohms (nominal impedence). When playing music the amp will not see exactly a 3 ohm, but will vary with music.

Also, since your amp is 4 ohms stable in bridged mode it might not like how you have the sub wired. You may have overheating issues. It's hard to say how much the amp would be putting out at 3 ohms (if it can handle it). Just because it's a lower impedence than 4 ohms (for 300 watts) doesn't necessarily mean it's going to put out more power. Amps can be designed to put out max power with a certain load on it, and won't always increase by decreasing the load (it often will, but not always).